Enable percentage of cost breakdown in BOM

IMPROVEMENT

The BOM of master items in Razor is ok but it does not allow for percentage of cost allocations to specific parts.  Not anymore.  Now, when you create a BOM, you can allocate a cost percentage to the part to build a true child - parent relationship.  Later, when you break down the item, you'll know exactly how much you're devaluing the parent item and how much you could potentially sell the child on the open market.